A number of attempts have been made in the past to use natural materials as polymeric building blocks. These have mainly centered on grafting natural materials such as sugars and starches with synthetic monomers. For example, U.S. Pat. Nos. 5,854,191, 5,223,171, 5,227,446 and 5,296,470 disclose the use of graft copolymers in cleaning applications.
Conventional graft copolymers have been produced by selectively generating initiation sites (e.g., free radicals) for the growth of monomer side chains from the saccharide or polysaccharide backbone (CONCISE ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING, J. I. Kroschwitz, ed., Wiley-Interscience, New York, p. 436 (1990)). These grafting techniques typically use Fe(II) salts such as ferrous sulfate or Ce(IV) salts (e.g., cerium nitrate or cerium sulfate) to create those initiation sites on the saccharide or polysaccharide backbone (see, e.g., U.S. Pat. No. 5,304,620). Such redox processes are not easily controlled and are inefficient. Also, cerium salts tend to be left in the resulting solution as unwanted byproducts, thereby presenting a potential negative effect on performance. Therefore, there is a need for natural materials as polymeric building blocks that do not provide those problems associated with graft copolymers.